X-ray tube



April 3 K. G. CATLIN 1,997,676

X-RAY TUBE Filed Feb. 11, 1935 5 Sheets-Sheet 1 INVENTOR TORNE April 16,1935. K. G. CATI .IN 1,997,676

. X-RAY TUBE Filed Feb. 11, 1933 5 Sheets-Sheet 5 -mnym INVENTORPatented Apr. 16, 1935 UNITED STATES PATENT OFFICE 18 Claims.

This invention relates to the class of devices known as X-ray tubes.

The objects of the invention are to enable the use of heavy current,without overheating of the focal spot, to maintain a desired sharp focusand to attain these and other advantages with a relatively simple,inexpensive and practical construction.

In previous endeavors, it has been proposed to make the anticathode as amovable electrode, so as to vary the surface subjected to bombardment ofthe cathode rays. Possibly, the best example is that form in which theanticathode element is in fact the rotor of an induction motorcooperatively disposed to an electromagnetic stator on the outside ofthe tube. Such constructions however, necessarily are expensive, have alimited useful life and must be handled and used with care.

The present invention is distinguished in particular from this mostsuccessful of the known movable target tubes by being of much simplerand more rugged design and consisting of fewer parts much less likely toget out of order.

The novel features of construction distinguishing the invention from thelast-considered and other known prior art, as well as the various newcombinations and relations of parts will appear as the specificationproceeds.

The drawings accompanying and forming part of the specificationillustrate a number of different possible embodiments of the invention,but it will be understood that the structure may be further modified andchanged all within the true spirit and broad scope of the invention asexpressed in the claims.

Fig. 1 is a broken sectional and partly diagrammatic illustration of aform of the invention in which the anticathode is constructed andmounted for movement after the manner of a pendulum.

Fig.2 is a. vertical sectional view of this form of-tube.

Fig. 3 is a partly broken view illustrating a modification of thependulum construction.

Figs. 4 and 5 are fragmentary and somewhat diagrammatic front and sideillustrations of a modification on the general lines of that firstshown.

Fig. 6 is a diagrammatic illustration of a reciprocating electrode formof tube.

.Fig. '7 is a broken diagrammatic illustration of an arcuate pendulumtype of the tube.

Figs. 8, 9, 10 are diagrammatic illustrations of an oscillating and twotorsional type of pendulum electrode tubes.

Fig. 11 is a diagrammatic representation of a pendulum type of tube withmovement to the target indicated as communicated by a magnetic inductionsystem.

Fig. 12 is an enlarged cross-sectional detail of the target as on linel2--l2 of Fig. 11.

Figs. 13 and 14 are views similar to Figs. 11 and 12 illustrative ofanother form of magneto induction operation.

Fig. 15 is a diagrammatic side representation of a form in which thetarget is suspended resiliently for the desired movement.

In the several views, the anticathode or target electrode is designated20, and it is supported in each instance, so that it may have a limitedswinging, oscillating or reciprocating movement with respect to thefilament or cathode. element 2|.

In Figs. 1, 2 and 3, the target element is an elongated arcuate membersuspended by a flexible resilient strip 22, of steel, copper, or thelike, secured to a suitable terminal block 23, sealed in the head of thetube structure 24. The tube or envelope is shown in the form of aflattened flasklike structure extended inthe direction of the swingingmovement of the pendulum and having a flat supporting base .25, enablingit to be solidly held as by suitable base clamps, such as indicated at26. 1

The face of the target may be a sheet or layer of tungsten as indicatedat 21, and thismay be backed up by a layer 28, of copper or, in. certaincases, by a layer of magnetic material such as iron.

In the first form of the invention, the backing layer is preferably agrade of magnetic iron and in this case, the pendulum movement isinitiated by an electromagnet 29, suitably supported on the outside ofthe tube in the line of movement of the target. To hold the target toswinging movement in a single plane equidistant at all times from thefilament, the suspending element 22, may be a ribbon of substantialwidth,-such as indicated, having a desired degree of transversestability.

One method of using the first form of tube is to draw the pendulum .upto one side by magnetic attraction and then, after releasing the targetto make the exposure through a suitable timer. 7

In Fig. 1, connections for this purpose are illustrateddiagrammatically, no attempt being made to show details of the timer andother circuit devices customarily employed in X-ray work.

The connections shown in Fig. l which may be considered primarilyillustrative in character involve first a suitable supply for thefilament or cathode element, the same being shown as including avariable transformer at 30, which may be connected in a convenientservice circuit, such as an ordinary lighting circuit.

The magnet for lifting the pendulum target is supplied with energy froma suitable source indicated at 3i, and the circuit for this magnet isshown as controlled by a hand switch 32, consisting of switch lever 32,which when engaged with its cooperating contact 33, is automaticallyheld in the switch closed relation by a holding magnet 34, in series inthe circuit. Part of the magnet circuit is made by switch contacts 35,36, the latter carried by a spring lever 31, which is equipped with apush button 33. The fixed end of this switch lever is connected in themagnet circuit at 39, and this same end of the switch lever is connectedat 40, with the timer 4|. The other side of this timer is connected at42, 43, with contact 44, positioned for engagement by contact 45, on theother side of the push button lever.

The timer is shown connected through a suitable circuit breaker 46, intothe 220 volt circuit 41, working through a variable auto transformer 48,high tension transformer and usually a rectifier 49, into the hightension side of the tube.

The operation will be understood from, the above. Upon closing themagnet circuit at 32, the magnet will draw the target to the side of thetube and hold it there until ready for the exposure. The exposure iscontrolled by simply operating the push button 38, which acts first tointerrupt the circuit through the holding magnet, thus releasing thetarget and then to close the circuit at 45, 44, through the timer, whichthereupon takes control and effects discharge at and for the time forwhich it has been set, from the filament to the then moving target.

For long exposures, the target may be kept continuously in movement, soas to thereby continuously present successive new focal spots. For theordinary, shorter exposures, only one swin or a portion of a singleswing of the target is sufficient.

The operation of the push button by interrupting the magnet circuit at35, 36, de-energizes the circuit holdingmagnet 34, thus automaticallycutting the target holding magnet out of action, until the magnetcircuit has again been purposely restored at the manual switch 32. Thisprevents magnet 23 from again coming into action upon releasing pushbutton 33, after making the exposure and the timer is usually soconstructed as to interrupt its own circuit after the exposure is made.Hence, any subsequent accidental or unintentional operation of the pushbutton will have no effect on the target. Relay 34 also may be used, ifdesired, to interrupt the timer circuit so that only one exposure can bemade for each closing of the hand switch 32.

The pendulum starting magnet may be set in the side of the tube and forinstance, be made as a solenoid coil mounted in a re-entrant portion ofthe tube, into which the target may swing and if continuous motion ofthe target is desired, automatic contact mechanism may be provided forenergizing the magnet coil in synchronism with swinging movements of thependulum.

Mechanical as well as electrical means may be provided for initiating ormaintaining swinging movements of the pendulum. Thus, in theconstruction illustrated in Fig. 3, a secondary pendulum on the outsideof the tube is used to set up the movements of the target pendulumwithin the tube. This outside pendulum is shown as consisting simply ofa pendulum weight 30, properly proportioned to the pendulum within thetube and fixed on the upper end of the pendulum strip 22 which in thiscase is an upward extension of the internal spring pendulum strip 22.

When the external pendulum 50 is vibrated by hand or by electrical ormechanical means, the target pendulum within the tube will start tooscillate proportionately and, with the target in motion, the exposurecircuit may be closed as by means such as shown in Fig. 1.

The form of the invention illustrated in Figs. 4 and 5, is generallysimilar to that first illustrated. The target however is of circularform and the oscillation may be initiated in this smaller type by simplyrocking the tube and then holding it rigid while the exposure is madeand the pendulum is in motion. For such purpose, the tube may be mountedfor swinging movement in a support, provision being made for stoppingand then rigidly holding the tube, such structure involving for example,the pivotal mounting of the tube on the swinging axis of the pendulumand a bell crank or the like for rocking and then securing the tube.

In Fig. 6, the movable target is a reciprocating element in the natureof a rod 5|, carried by a solenoid core 52, operating in coil 53, thistarget rod being angularly related to the cathode element 2i. Suitablecircuit arrangements such as above described, may be used for settingthe target into movement and effecting the desired timed exposure whilethe target is in movement.

The construction shown in Fig. 7, involves a modification of thependulum type of target first disclosed, in that the cathode rays arereflected from the arcuate end surface 54, instead of from the flat sideface of the target, and in that the tube is double-ended and horizontalmore like conventional types.

Fig. 8 illustrates a smaller form of tube, such as shown in Fig. 7, witha circular filament type cathode instead of spiral type, focused on thearcuate end face of the target.

Figs. 9 and 10 illustrate torsion type target pendulums involving fiatdisc targets 3|, either directly suspended from the torsion pendulum rod56, as in Fig. 9, or suspended therefrom through the medium of a spiralspring 51, for increasing the amplitude of movement. In theseconstructions, the target movement may be initiated and/ or maintainedby rotating the tube on its axis by mechanical or other means, first inone direction and then in the opposite to store up and release torsionalforces in the pendulum.

Figs. 11 to 14 illustrate forms of the invention similar to the first,in which the pendulum action is started by magnetic induction. In Figs.11 and 12, a coil 53 is located outside the tube in position to inducecurrents in the body of the target serving by the repulsive action thusset up to swing the target and hence generate the movement desired inthe making of the exposures. Fig. 11 also illustrates how the suspensionmay include a free swinging link at 53, to enable the pendulum tooscillate more easily.

In Fig. 13, a reversed condition is illustrated, the actuating coilbeing mounted on the pendulum and co-acting with a fixed metallic body60, outside the tube and which latter, if desired, may have a suitableopposing winding 6|, associated therewith. Flexible leads are indicatedas 62, for the coil connections within the tube, thesame being'locat'edadjacent the swinging axis, of the pendulum strip.

Fig. illustrates a further modification in which the target movementismade possible by suspending the target element on an extensible andcontractible spring 63. In this case, the desired movement may beinitiated and/or maintained by reciprocating the tube, by hand orotherwise, and then holding it rigidly, with the pendulum in verticalmovement 'while the exposure is being made.

The .vibration or swinging of the target, whether. the motion beoscillatory as in the case of the swinging pendulum construction, orreciprocatory, as in the plunger or spring suspended forms, or rotary asin the case of the torsion pendulum forms, provides a changing surfacefor the focal spot, enabling heavy current to be employed withoutburning in the anticathode surface and this is all accomplished in arelatively simple, inexpensive and rugged construction adapted withreasonable use to last indefinitely. The gravity swing or travel of thetarget gives a desired constancy or regularity of movement and the timercan be controlled to cut in the exposure in the desired period oftravel, in the intermediate portions of the swing. The timer thus maycontinue in control during a plurality of swings, effecting the desiredexposure or exposures and in the desired portions of each swing. Variousother means may be employed for initiating or maintaining the swingingmovement. As one example, the electromagnet may be bipolar and supporteddirectly beneath the arcuate target and shiftable from this position upto one side, so that. when energized, it may be used to magneticallydrag the pendulum from the bottom position any desired extent up to oneside and then released from such selected position. As anothermodification, the pendulum may be caught and held by a small latch ofmagnetic properties, which can be tripped when desired by anelectromagnet on the outside of the tube. Also, the. so-calledsympathetic vibration effects may be utilized to start the penduluminside the tube swinging from a like pendulum located outside the tube,alongside the one inside.

What is claimed is:

1. An X-ray device, comprising in combination, an envelope, cathode andanticathode elements. therein and mounted one to swing as a freependulum with respect to the other and with the anticathode surfaceconstantly in the same relation in respect to the cathode element andmeans for selectively timing the discharge between the elements todifferent periods in the swinging of the free pendulum element.

2. An X-ray device, comprising in combination, an envelope, cathode andanticathode elements therein, said anticathode consisting of a suspendedfreely swinging pendulum having a target surface disposed in the sameconstant relation to the cathode element in all positions of itspendulum swinging movement.

3. An X-ray device, comprising in combination an envelope, cathode andanticathode elements therein, said anticathode consisting of a suspendedfreely swinging pendulum having a target surface disposed in the sameconstant relation to the cathode element in all positions of itsmovement, means for effecting swinging movements of the pendulum andmeans for selectively timing the discharge in the course of saidswinging movements.

4. An X-ray device, comprising in combina- 5 tion, an envelope, cathodeand anticathode elementstherein, said anticathode consisting of aswinging pendulum having a target surface disposed in the same constantrelation to the cathode element in all positions of its movement and 10an electric coil outside the envelope and within the range of influenceon the pendulum anticathode inside the envelope.

5. An X-ray tube, comprising an envelope having a neck and a widenedbase, a pendulum anti- )5 cathode suspended from the neck of theenvelope and adapted to swing in the widened base portion of theenvelope and a cathode element mounted in the widened base portion ofthe envelope in cooperative relation to the face of 20 the pendulumanticathode.

6. An X-ray tube, comprising an envelope having a neck and a widenedbase, a pendulum anticathode suspended from the neck of the envelope andadapted to swing in the widened base portion of the envelope, a cathodeelement mounted in the widened base portion of the envelope incooperative relation to the face of the pendulum anticathode andelectrical means on the outside of the envelope and cooperating with theanticathode therein to swing the same to one side of the envelope.

7. An X-ray tube, comprising an envelope having a neck and a widenedbase, a pendulum anticathode suspended from the neck of the envelope andadapted to swing in the widened base portion of the envelope, a cathodeelement mounted in the widened base portion of the envelope incooperative relation to the face of the pendulum anticathode, electricalmeans on the outside of the envelope and cooperating with theanticathode therein to swing the same to one side of the envelope andmeans for then releasing the pendulum anticathode and for automaticallyinitiating discharge of the tube with the pendulum anticathode inmovement.

8. In X-ray apparatus, a target comprising a target element and a springsupport strip rigidly secured to said target at one end and rigidlysupported at the opposite end, said strip being of substantial width andpossessed of sufiicient transverse stability to maintain the targetelement swinging in a definite fixed path, a cathode focused on saidtarget element and positioned at a continuous fixed distance from saidpath of movement and an envelope for said target and cathode.

9. In X-ray apparatus, a target comprising a target element and a springsupport strip rigidly secured to said target at one end and rigidly sup-0 ported at the opposite end, said strip being of substantial width andpossessed of sufficient transverse stability to maintain the targetelement swinging in a definite fixed path, a cathode focused on saidtarget element and positioned at a. continuous fixed distance from saidpath of movement, said target element being elongated in said path ofmovement to thereby provide a continuous target surface throughout therange of travel afforded by the spring supporting strip and an envelopefor said target and cathode.

10. In X-ray apparatus, a target comprising a target element and aspring support strip rigidly secured to said target at one end andrigidly supported at the opposite end, said strip being of submovementand an enclosing tube having a re-' stricted neck supporting the rigidlyheld end of the spring supporting strip and a widened portion about thepath of movement of the target.

11. An X-ray device, comprising a target element having a fiat face andan arcuate face, means supporting said target to swing with said fiatface in a fixed plane and said arcuate face following a definite arc ofmovement, a cathode focused on said fiat face of the targetand anenvelope for said target and cathode.

12. An X-ray device comprising a target element having a fiat face andan arcuate face, means supporting said target to swing with said fiatface in a fixed plane and said arcuate face following a definite arc ofmovement, a cathode focused on said arcuate face of the target and anenvelope for said target and cathode.

13. An X-ray device, comprising a target element having a fiat face andan arcuate face, means supporting said target to swing with said flatface in a fixed plane and said arcuate face following a definite arc ofmovement, a cathode focused on one of said faces of the target, meansfor initiating free swinging movement of said target and an envelope forsaid target and cathode.

14. An X-ray device-comprising an envelope, cathode and anti-cathodeelements therein, one mounted to swing as a pendulum with respect to theother and a pendulum outside the envelope constructed and arranged toeffect swinging movements of the pendulum element within the envelope.

15. An x-ray device comprising an envelope, cathode and anti-cathodeelements therein, a flex-- ible pendulum strip supporting one of saidelements to swing as a pendulum within the envelope, an extension tosuch pendulum strip outside the envelope and a pendulum weight on saidoutside extension for enabling pendulum movements of said extension toimpart swinging movements to the pendulum element within the envelope.

16. An X-ray device comprising an envelope, cathode and anti-cathodeelements therein, one mountedto swing as a pendulum with respect to theother, a timer connected to control discharge across said elements inthe swing of the pendulum element and means for initiating swingingmovement of the pendulum element and substantially simultaneouslycutting said timer into control of the discharge of the tube.

17. An X-ray device comprising an envelope, cathode and anti-cathodeelements therein, one mounted to swing as a pendulum with respect to theother, a timer connected to control discharge across said elements inthe swing of the pendulum element, means for initiating swingingmovement of the pendulum element and substantially simultaneouslycutting said timer into control of the discharge of the tube, said meansincluding an automatic circuit breaker requiring restoration beforeagain initiating the pendulum movement and timer control.

18. An X-ray device, comprising a vibrating target mounted for freearcuate swinging movement in a definite fixed path, a cathode focused onsaid target, said target having an arcuate target surface elongated insaid path of target movement and an envelope for said swinging targetand cathode.

KENNETH G. CA'I'LIN.

